The machines necessary to deal with the shaping and dressing of stone for building purposes are not very numerous. They are, however, most important, as by judicious use of machinery in this department of the works great economies can be effected. The first necessity in this connection is the Frame Saw. This may be either hand or power driven. The more familiar hand-driven type is shown in Fig. 254, and consists of a rectangular frame the sides of which are made of wood, as is also the centre bar, the top of the frame being of twisted rope to give the necessary tension to the saw blade, which forms the bottom member of the frame. From a ring in the centre of the top of the frame a cord is taken up and over a pulley, held by a pole as shown, when no other fixture is available, and to the other end of this cord a weight is attached. This has the effect of relieving the saw blade of some of the weight of the frame.

Stone Cutting Machines 286

Fig. 254.

Stone Cutting Machines 287

Fig. 255.

Fig. 256

Fig. 256.

The saw is operated by giving it a reciprocating motion by hand, and at the same time allowing a slight stream of water to flow over the blade and into the cut in the stone to act as a lubricant, keep the saw cool, and carry away the stone dust, which would otherwise clog together and stop the motion of the saw.

The same apparatus can be easily arranged to be driven by power (Fig. 255), the reciprocating motion being obtained by means of a revolving disc and crank pin and a connecting rod. Five or six of these saws can be fixed together in one main framework, all driven from the same shaft. They are so arranged as to be adjustable with regard to their distance from one another, and by means of this apparatus a large block of stone can be sawn into five, six, or more slabs of a given thickness in one operation.

The Stone-Dressing and Moulding Machine (Fig. 256), with its various appliances, adjustments, and attachments, will carry out practically all the operations necessary on the rough stone to bring it to a finished state. Of course, it must be understood that many cases arise in which hand work by masons is absolutely essential, but the foregoing remarks apply to nearly every form of straight moulding and flat dressing.

By reference to the illustration it will be seen that the machine consists of a flat cast-iron bed-plate, running in grooves on rollers, motion being communicated to it from a belt by means of heavy gearwheels. Two upright brackets carry the cross-head which contains the tools for working the stone. The bed travels backwards and forwards, automatically changing its direction at the end of the working stroke; this being brought about by means of stops, adjustable in the slot at the side of the bed, which operate the belt-shifting gear, which in turn reverses the motion.

The cross-head can be raised or lowered slightly to alter the depth of the cut by means of the rope and rope-wheel shown at side; or if it has to be raised clear to put fresh work on the table, the belt-driving gear is brought into play and the crosshead quickly run up out of the way.

By an ingenious device the cross-head is made to "throw over" or reverse its position, and at the same time the position of the tools with regard to the stone, at the end of each stroke, so that the cutters work in both directions and no time is lost on the return stroke.

The machine shown is fitted with a patent rocking table, by means of which a stone can rapidly be turned any side up or set at any angle for working. This appliance is of great importance, as without it a great deal of time is taken up in packing and adjusting the work until it is at the required angle.

Beyond the saws and moulding machines very little more actual machinery for stone working is required; a stone rubbing bed for giving flat, true surfaces, although very necessary, scarcely being in any sense a machine, and the large nail-head and other machine-driven saws, used for hard stone, being more employed by quarry owners than general building contractors.

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